Isotope effects of europium in ligand exchange system and electron exchange system using ion-exchange displacement chromatography

Abstract

The ion-exchange chromatography of europium has been carried out to study the europium isotope effects in a ligand exchange system (LXS) and an electron exchange system (EXS). In both cases highly acidic cation-exchange resin (AG-MP 50) with 100–200 mesh size particles was used. In the case of LXS, where EDTA was chosen as a ligand for Eu 3+ ions, the heavier isotope 153Eu has been enriched at the front boundary of the europium band. Such findings mean that the heavier isotope 153Eu is preferentially fractionated into the EDTA complex form in the solution phase. In the EXS, where Eu(II)–Eu(III) exchange reaction takes place, the heavier isotope 153Eu has been observed to be enriched in the front part of the europium band. The result shows that the heavier isotope is preferentially fractionated in the Eu(II) solution phase. The values of the single stage separation coefficients ( ε= S−1) of the 153Eu/ 151Eu isotopic pair have been calculated for LXS as 1.48·10 −5 at 80°C and for EXS as 2.13·10 −4 at 60°C.